Party line selective signaling system having code call



- R. w. JONES 0 PARTY LINE SELECTIVE SIGNALING SYSTEM HAVING CODE CALLFiled Deo. 50, 1947 4 Sheets-Sheet 1 Oct. 16, 1951 L/NE E OU/PME NT 0 TTHER FINDER FINDER C NNECTOR L INKS To OTHER FINDERS BUSY SW ALL LINKEXECUTIVE LOUD SPEAKER SYSTEM FIG. I INVENTOR. Roy W Jones 1951 R. w.JONES 71, 50

PARTY LINE SELECTIVE SIGNALING SYSTEM HAVING com: CALL Filed Dec. 30,1947 4 Sheets-Sheet 2 CONNECTOR 22 I26 LAST LINK All INTERMEDIAT:

LINK

2 INVENTOR.

Roy W. Jones Oct. 16, 1951 R. w. JONES 2,571,250

PARTY LINE SELECTIVE SIGNALING SYSTEM HAVING CODE CALL. Filed Dec. so,1947 Y 4 Sheets-Sheet a 300 Q CODE CALL F I 3/! 346 NDER 351 7 M L 206MULT. To OTHER I l I 37l- L\372 1 C344 CONNECTORS I T I DIAL TONE I 345343 F l I I I I 388; I I I 389 6005 SOUNDERS l I 3B2 374/ 383 V366 3734P I 44L 90 39! ljlaw l 349 E 39%I E I V l I 370 395 338 SPECIAL 328 l3 3com; LL 339 FIG; 3 ALARM 394 INVLNTOR. Roy W Jones Arty FIG. I FIG. 2FIG.3 A764 4 Sheets-Sheet 4 R. W. JONES PARTY LINE SELECTIVE SIGNALINGSYSTEM HAVING CODE CALL CODE CALL 0 44/ J Oct. 16, 1951 Filed Dec. 30,1947 STORAGE RELAYS FIG. 4

. INVENTOR.

Roy W Jones BY I Patented Oct. 16, 1951 PARTY LINE SELECTIVE- SIGNALINGSYSTEM. -HAVING CODE CALL Roy W.,J nes, Rochester, N. 1 assignor toAutomatic Electric Laboratories, Inc., Chicago, 111., a corporationofDelaware Application December 30, 1947,.Seria1'No. $795,482

13 Claims. 1

This invention relates to .automatic telephone systems in general, butis concerned more particularly .with small systems of the type which,are commonly known as private automatic exchan es, or as a P. A. X.Exchanges of this znatuream usually installed by private concerns, andin order to meet the more exacting requirement of the subscriber inthese small systems, it, isoftennecessary to provide certain specialfeatures which :are unnecessary in a large public exchange. The presentinvention is concerned with certain of said special features commonlyknown as code call and executive cut-in.

The principal object of the invention is to providethe above-namedfeatures without materially increasing the cost of the equipment, whileretaining simple, efilcient and modern high-class telephone service.

A-feature of the invention relatesto certain new and improved circuitarrangements, whereby,

code call, executive cut-in and local-to-local service are provided forsatisfactory service.

Another feature relates to code call service, whereby, the code callnumber is dialed and a :rotaryswitch is operated responsive to saiddialiing. Upon receipt of the first digital series of pulses, the switchoperates and selects one of .a :first group of storage .relays forstorage of the :firsudigit'dialed. The switch restores to normal andreoperates upon receipt of the second series :of .digital pulses forselecting one 'of a second group-:of storage relays for storage of thesecond digit dialed. The switch again restores to normal. :Otherfeatures, together with the vones named above, :will be explained morein detail herein- .after, reference being had :to the .acompanyingdrawings which show by means of the :usualcircuitdiagrams a sufficientamount of-the appara- :tus to enable the invention to be .describedandunderstood.

Referring now-to the drawings and ;F;igures 1 to 5, inclusive:

Figure lshows two lines such as L- and L-26 with each line shown as aparty line having .sub-

scribers H, H' ,.J and J respectively. Each sub- ,scribers stationconsists of the usual and .well- A known equipment common to automaticsystems, therefore only the ringers at each station have beenshown asbeing connected to opposite sides of .the lines. Each line contains anindividual line and cut-off relay which tends to operate as .a two-steprelay, the first action being that of an ordinary line relay. The finderportion of one of the finder-connector links is shown, as well as thefirst relay of the relay call allotter. Subscriber .Hisrassumed to be anexecutive and is therefore shownhaving a push button which provides theexecutive with the special services of executive cut-in, Connections arealso shown connecting "the'executives"line to an executives loudspeakersystem such as disclosed in U; S Patent No.

2,225,477, issued December 1 to Roswell H Herrick. The finder shows .twosets of contact banks Of 26 points each for terminating the lineconductors control conductors and extra control conductors, so arrangedthat when one ,set of having a rotary switch of the same typeandconstructiomas the. finder except for the wipers.

Figure 3 shows ,the code call finder and the code sounding apparatus ofthecode call eguipment.

Figure 4 shows the ,remainder ,of the code calling equipmentwhich-includes the storage ,re-

lays and the rotary-switch.

Figure ,5 vis a' figure-number i,-iagram used -in conjunction with thedrawings, so that when the awings ar arrang d asshowh, the system wi bebetter understood.

Referring more particularly, now ;to Figures 1 and 2 of the drawings, itwill be seenthat-the first on s of the doublefsets of zcontactbanks ofthe-finder and connector serye the Afirstgroup ,of lines fand that. thesecond setof ,the double convtacthanks-serve the second g-roup ,oflines. The

following table has been inserted to show the relationship betweenthe-switch bank terminals land'the call numbersof each line group.

TABL'E.'OALL "NUMBERS First Group of Lines ,SeoondGroup of Lines .;?w.-,au% 1 emnna S Second Second th ty vParty lE s ar y Party Ring reversing*Ring revers- Not used 1 Il Wiper switching Notused Not used I3(Gode-Ca11- 21 -111 4 13 .22 112 5 14 -23 113 32 .111 7 16V .25 g 1.15.8 17 -26- 116 Not used Not used Notmsed; Not-psed 91 181 w 271 1, 171 192. 182 272 1,172 .1 .31 1. 94 ,184 i274 1,174 .95v 185 275 1,175 96186. 276- ,1, 176 97 187 277 '1, 177 ,98 2 188 .2781? 21; 1:78 99 139 279 ,1 ,-1 79 Not used Not used Not used 'Not'used .901 :1, 801 2,1701 111;.701 902 1, 802 2,,702 11,- 702 903 1, 803 2,703 11, Z03 j 4 1 80512,7041 11,704 1, 805 305 11, 705 06 11; 706 (Co -Ga ,Ans.

"Normal position *Normal position In referring to the table, it will beseen that the first terminal, of the first line group switch bank, isused as a ring reversing terminal, the second terminal of the same .bankis used for wiper selecting, or group selecting and the third terminalof the same bank is used to initiate a code call. Corresponding firstand second terminals of the second line group switch bank are not usedand the third terminal is connected to a second group line. Therefore,the first line (line 1) is actually connected to the fourth terminal ofthe first line group. Line 5 is connected to the 8th terminal of thefirst line group and contains subscriber H and H. The 25th terminal ofthe first line group is used only for answering a code call and as the9th and 19th terminals are not used, it ma be seen that the first linegroup contains lines 1 through 19. In the second line group, the thirdterminal is the first to be connected to a line so therefore correspondsto line 20. Line 26 is connected to the 10th terminal and containssubscribers J and J. The 9th and 19th terminals are not used and as the25th terminals are, it may be seen that the second line group containslines 20 through 40. Thus it will be noted that the system can serve amaximum of 40 two-party lines.

The call allotter is of the all-relay pre-selecting type, in that aseach time a call is initiated and received, the next idle relay set insuccession is used to start an idle finder hunting for the callingline.After the last link in the group has been used, it completes a chaincircuit to the reset relay such as IE0, which operates and completes acircuit to all the relays corresponding to I50 and I50 of idle relaysets, thus making the links preselectable to start their associatedfinders to hunt for the calling lines as the links are again used insuccession.

' The rotary switch of the finder is of the non-' numerical type and isnon-homing, whereas, the rotary switch of the connector is of thenumerical type and restores to its home position after each time theconnector is used. From the connector rotary switch it will be notedthat the th 'terminals of the contact banks corresponding to the firstline group are used as the code call answering terminals, while thethird contact of the contact bank corresponding to the first line groupof the control conductor is used for the code call initiating terminals.

It will be noted that the battery feed and ring reversal relay such as200 serves two definite purposes; first, in that it provides talkingbattery potential for the called party, and second, it

routes ringing current over the opposite line conductor when the secondparty on a party line is called, in addition to providing talkingbattery.

Referring now to Figures 3 and 4, it will be noted that only thesubscribers having their extra control conductors, (E. C.) switch as I24connected to the contact bank accessible by the extra control wiper suchas 398 of the code call finder, can initiate a code call. Only two codesounders such as 390 and I have been shown, however, any determinednumber may be used depending upon the size and type of structures withinwhich the exchange is installed. The rotary switch in the code callfinder is shown having point contact banks, however, double 26 pointcontact banks as shown in the regular finder (Fig. 1) may be used. Thecode selecting rotary switch may be any convenient size with eachconsecutive 7th contact being dead, only the first six contact terminalsare shown connected to the equipment.

The six storage relays are divided into two groups, with relays 450, 460and 410 in the first group and relays 480, 490 and 415 in the secondgroup. Each code call number is a two-digit number and may range from 11through 66, thus providing a maximum of 36 code call numbers. Whendialing a code call number, the first digit operates one or more of thefirst grou of storage relays and the second digit operates one or moreof the second group of storage relays. For example: In the first groupof storage relays if the digits 1, 2 or 3 are to be stored, the relays450, 460 or 410 are operated, while if the digits 4, 5 or 6 are to bestored, the relays 450 and 460, 450 and 410 or 460 and 410 are operated.In the second group of storage relays if the digits 1, 2 or 3 are to bestored, the relays 480, 490 or 415 are operated, while if the digits 4,5 or 6 are to be stored, the relays 480 and 490, 480 and 415 o 490 and415 are operated.

Local to local calls The ensuing description will cover the operation ofthe illustrated equipment in Figures 1 and 2 during the initiation andcompletion of a local to local call.

Referring to the above-mentioned figures, it will be noted that thenegative and positive talking conductors of the first line groupterminate at respective first and third bank contact sets and thenegative and positive talking conductors of the second line groupterminate at respective second and fourth bank contact sets. It willalso be noted that the talking conductors of line L5 are connected tothe eighth contacts of the banks corresponding to the first line groupand the talking conductors of line L26 are connected to the tenthcontacts of the banks corresponding to the second line group. It will befurther noted that subscribers H and J are the first parties on theirrespective lines and subscribers H and J are the second parties on thesame said lines.

Referring to the table included in the forepart of the specification, itwill be seen that the call numbers of subscribers H (contact #8) and J(contact #10) are 8 and 271 respectively, while the call numbers for Hand J are 17 and 1171 respectively.

Assuming that subscriber H, of line L5 in the first line group, desiresto call subscriber J, of line L26 in the second line group, theequipment will operate in the following manner:

As subscriber H removes the receiver a loop circuit is closed acrosstalking conductors I66 and I61, thereby, completing an operative seriescircuit for relays I I0 and I10, this circuit extending from ground atcontacts II2, lineconductor I61, the closed loop, line conductor I66,contacts III, upper winding of relay H0 and down through the winding ofrelay I10 to battery.

In operating X contacts I I3, relay IIO applies a marking batterypotential supplied from its lower winding over conductor I88 to the 8thcontact of the bank set terminating the first line groups controlconductors. As relay H0 is a combined line and cut-off two-step relay,its first step of operation is now completed. In operating contacts I1I,relay I10 completes a circuit to the line relay I20, this circuitextending from ground at contacts I62, contacts I1I, resistance RI,contacts I52 and up through the upper winding of relay I20 to battery.At contacts I12, a busy test circuit is completed for testing for anall-link busy condition through contacts connected in series in eachrelay set.

At contacts I21, relay I prepares. a battery feed circuitfor the calledparty, at contacts I22 an obvious circuit is completed for the holdrelay I and at contacts 'l itopens a point. in the pulsing circuit.

It will be remembered that the calling line applies battery to thecorresponding contact of the controlbank set over conductor I88, whileall idle and busy lines apply ground to their respective contacts.

In operating contacts I3I, relay I30 applies a ground potential for useby other relays in the finder-connector link, at contacts I32 a circuitis completed for the motor magnet I80; this circuit extending fromground at a contact terminating the control conductor of an idle or busyline, or (as shown) the grounded 26th contact, wiper I95, contacts I43,I32, conductor II9, contacts 23I, conductor Hi0, contacts I8I andthrough the winding of motor magnet I80 to battery. At contacts I33 acircuit is prepared for the cut-through relay 220, at contacts I34 thehoming circuit for motor magnet 280 is opened and at contacts I35 apoint in the pulsing circuit of magnet 23!! is prepared.

In operating, motor magnet I80 opens contact I8I, thereby breaking itsown energizing circuit and thus the magnet I853 restores. Assuming thatwipers I92, I 94, I06 and I98 are resting on their respective 26thcontacts and that wipers I0 I, I93, I05 and ISI are not engaged with anycontact (as shown) as magnet I88 restores, wip ers I9I through I08inclusive are advanced one step. Wipers I9I, I93, I95 and I9! thenengage their respective first contacts and wipers I92, I94, res and I98are not engaged with any contact. In completely restoring magnet I80compl-etes its own circuit at contacts I'SI. In operating, magnet I8 3opens its circuit at contacts I8I and thus restores. In restoring,magnet I80 advances its wipers a second step and in completelyrestoring, completes its own circuit again at contacts I81. This selfinterrupted action between magnet i'B'fi and its contacts IBI continuesuntil it has rotated wipers IE, I 93, I95 and I9! into engagement withcontacts number 8 which terminate the conductors of line L5 and thecalling subscriber H.

As wiper I95 engages its 8th contact, it encounters the batterypotential supplied from the lower winding of the line and cut-oil relayI I0, thereby completing a circuit for the relay I40 through its upperwinding. This circuit extending from ground at contacts I3I, conductor5, contacts 26-! or 221, conductor H8, contacts I35, the upper windingof relay I40, centacts I'43,wiper i055 and engaged contact, conductorI88, X contacts H 3 and through the lower winding of relay I I-0 Y tobattery.

In operating, relay I40operates X contacts I ahead of the othersandlocks itself operated byway of ground at contacts I3I, conductor II5,contacts 26-? or 221, conductor IIB, X contacts I45 and the lowerwinding of relay I40 to battery. At contacts MI and I42 relay I40connects the talking conductors of subscriber H to the line relay I20and completes a dial tone circuit to the calling subscriber H, atcontacts I43 the circuit through the upper winding of relay I40 isopened, at contacts I'44 a circuit is completed for the second stepoperation of the line and cutoff relay IIO, this circuit extending fromground at'contacts I44 over a previously traced circuit and through thelower winding of relay 0' to battery. At contacts I46, relay I40prepares-a 6. circuit for the series relay 2.1 0, at contacts I41preparesv a busy tone circuit for the first link (as shown) while in.use and at contacts I48 opens the circuit to relay I50 oi the allotter,allowing relay I50 to restore.

In completing its second step operation,

relay I I0 opens its original operating circuit at contacts II I and II2 thereby allowing relay I10 torestore.

In restoring, relay-I50 prepares the start circuit tothe next idlelinkin rotation at contacts I'5I, atcontacts I52 the previous energizingcircuit tothe line relay I20 is opened, at contacts I54 prepares afuture circuit for itself and at contacts I55 prepares. a circuit to thereset relay I IiIl. In restoring, relay I'I0 opens a point in theenergizing circuit of the line relay I20. Line relay I20, however,remains energized now from ground through its lower winding, thepositive talking conductor, the closed loop of subscriber H, thenegative talking conductor and through the upper winding of relay I20 tobattery.

Upon receipt of dial tone, subscriber H prepares to dial the first digit2 of the call num ber 2II. Line relay I20 will operate in the usual andwell-known manner and deenergize and energize two times in response todialling digit 2. At the beginning of the first pulse, line relay I20restores and opens the circuit to the hold relay I 30 at contacts I22.Relay I30 is constructed as being slow-to-release and therefore remainsoperated during dialing. At contacts I23 relay I20 completes circuitstothe series relay 2 10 and the motor magnet 280; these circuits extendingfrom ground at contacts I23, contacts I35, conductor I31, contacts 255,230 and (1) to the left over conductor I38, contacts I46, conductor I49and through the upper winding of relay 210 to battery; and (2) downthrough the winding of motor magnet 280 to battery.

Relay 210, in operating, prepares a busy-test circuit by way of contacts272 and at contacts 215 shunts its lower winding sothat relay 210 is nowslightly slow to release and thereby remains 0perated during the pulsingof each dialed digit. Motor magnet 280 energizes and deenergizes witheach deenergization and energization of the line relay I20. Magnet 280advances its wipers 232 through 239 inclusive a single step each timemagnet 280 restores, therefore at the end of the first digit, wipers 232through 239 inclusive are engaged with their respective second contacts.

The series relay 210 restores after the first digit has been dialed andat contacts Z'II a circuit is completed for the wiper selecting relay240; this circuit extending from ground at contacts 220, conductor I28,contacts I 33, conductor III), contacts 265, 253, the lower winding ofcut-through relay220, contacts 2', 241, wiper 236 and engaged'secondcontact and the lower winding of relay 240 to battery. The resistancesof the windings of relays 220 and 240 are so arranged that relay 220will notoperate over the above-traced circuit.

In operating X contacts 245, relay 240 locks itself operated by way ofground at contacts I3I, conductor II5, X contacts 245 and through theupper winding of relay240 to battery. At contacts 242, 244 and 246,relay 240 selects the second line group in which the called party islocated.

The second digit 7 of the call number 2'II is now dialed andline relayI20 restores and reoperates a total of seven times. Upon receipt of thefirst pulse, relay I20 operates as de scribed before, completing acircuit to the series relay 210 and the motor magnet 280 as previouslytraced. Relay 210 operates as previously described and magnet 280operates each time line relay I20 restores and restores each time linerelay I20 reoperates, therefore, after receipt of all the pulses of thesecond digit 7, wipers 232 through 239 inclusive have been rotated anadditional seven steps and are now engaged with their respective 9thcontacts. Series relay 210 and motor magnet 280 have again restored.

The third and last digit 1 of the call number 21I is now dialed and thesame operations occur as previously described. Motor magnet operates inresponse to the operations of the line relay I20 and wipers 232 through239 arerotated one more step so that nowthe wipers are engaged withtheir respective tenth contacts of the second line group and whichcorresponds to the called line.

Before the series relay 210 restores a busy test circuit is completedand should the called line be busy, wiper 231 would encounter ground atits 10th contact, which terminates the control conductor of the calledline; this ground would complete an operative circuit to the busy relay250 which would be traced from wiper 231, contacts 246, 212, and throughthe winding of relay 250 to battery.

It isassumed, however, that the called line is not busy and thereforewiper 231 will encounter a battery potential at its 10th contact. Whenthe series relay 210 restores, a circuit is completed for thecut-through relay 220 at contacts 21I. This circuit may be traced asfollows: from ground at contacts 229, conductor I28, contacts I33,conductor II6, contacts 265, 253, the lower winding of relay 220,contacts 21I, 246 and wiper 231 to battery through the winding of lineand cutoff relay I00 and the control conductor I of the called line.

In operating X contacts 223, relay 220 locks up from ground at contactsI3I over conductor II5, X contacts 223 and the upper winding of relay220 to battery. At contacts 22I and 222, relay 220 prepares forextending the call through to the called line, and ringing current istransmitted to the called line. This ringing circuit may be traced asfollows:- battery from interrupted generator, through the upper windingof the ring-cut-off relay 2I0, contacts NI, 2, 2 2I, 242, wiper 233 andengaged tenth contact, the negative talking conductor I16 of the calledline, cable C-I64, conductor I16 and through the ringer at station J toground. At contacts 224,

225 and 226, operation of the executive cut-in relay 260 in the presentbusy finder-connector link is prevented. At contacts 228 a busyingground is applied to the connector control terminals for busying thecalled line to other connectors, at contacts 230 the pulsing circuit tothe series relay 210 and the motor magnet 280 is opened and at contacts23I a further point in the circuit to motor magnet I is opened.

The called line is now rung and after a reasonable period of time, thecall is answered by the called party. The answering shunts the ringerand connects direct ground to the upper Winding of the ring-cut-offrelay 2I0, thereby causing the relay 2I0 to operate. In operating X"contacts 2 I5, relay 2 I 0 locks up to ground at contacts I3 I; atcontacts 2 I2 and 2 I4 the extension of the call is completed and acircuit is completed to the combined battery-feed and ring reversalrelay 200, this circuit extending from ground throush the lower windingof relay 200, contacts 2 I4, 222, 244, wiper 235 and engaged tenthcontact, the positive talking conductor I11 of the called line, cableCI64, conductor I11, the closed loop at station J, the negative talkingconductor I16 of the called line, cable CI64, conductor I16, wiper 233and engaged tenth contact, contacts 242, 22I, 2I2, I2I and through theupper winding of relay 200 to battery and at contacts 2 I6 relay 2I0opens an alternate circuit for the upper winding of relay 200.

The conversation may now proceed with the line relay l20-supplyingtalking battery to the calling subscriber and the battery feed relay 200supplying talking battery to the called subscriber.

After conversation is completed, both subscribers replace theirreceivers and the equipment will restore in the following manner: Assubscriber H replaces his receiver, line relay I20 restores, which inturn releases hold relay I30. As relay I30 restores, relays I I0, I40,2I0, 220 and 245 release and as either or all of the relays 2 I0, 220and 245 restore, relay 200 releases. In restoring contacts 229 and 230,relay 220 completes a homing circuit for motor magnet 280; this circuitextending from ground at contacts 229. conductor I28, contacts I34,conductor I39, the multiple connected bank contacts engaged by wiper239, wiper 239, contacts 28I, 230 and through the winding of magnet 280to battery. Magnet 280 operates and interrupts this circuit at contacts28I, which causes magnet 280 to deenergize and step wiper 239. Thisinteraction of magnet 280 continues until wiper 239 has engaged contact26, which maintains the magnet circuit open, thus all wipers 232 through239 are at normal.

The equipment is now at normal and in condition to handle future calls.Before continuin with the next section, a short description of thecombined operation of the battery-feed and ringreversal relay 200 willbe covered. The operation just described covered the operation of relay200 operating only as a battery-feed relay. Relay 200 will operate onlyas a ring-reversal relay when the second party of either line group iscalled, hence the first digit of a call number of a second party ofeither line group is the digit 1.

Assuming now that a calling party desires to call a second party of oneof the line groups, the equipment will operate the same as justdescribed, until the calling party dials the first digit of the callnumber, which now is the digit 1. After the digit 1 is dialed, linerelay I20 will restore and reoperate once causing motor magnet 280 toadvance its wipers 232 through 239 one step so that now the wipers havebeen rotated off their normal positions and engage their respectivefirst contacts. As wiper 236 engages its first contact, an operativecircuit is completed for relay 200 which may be traced from ground atcontacts 229, conductor I28, contacts I33, conductor II6, contacts 265,253, lower winding of relay 22 0, contacts 21I-, 241, wiper 236 andengaged first contact, resistance R3, resistance R2 and through theupper winding of relay 200 to battery. Relay 220- does not operate,however, due to resistances R2, R3 and the resistance of the upperwinding of relay 200.

In operating X contacts 205, relay 200 completes an obvious lockingcircuit for itself, at contacts 202 and 204, ground potential is removedfrom the positive conductor of the called line and applied to thenegative line conductor and at contacts MI and 203 rinsing current isreroutedfrom the negative called line conductor to the positive lineconductor.

The remaining digits of the call number may now be dialed and the systemwill operate as previously described. As the cut-through relay 220 isoperated subsequent to the completion of dialing, the closing ofcontacts 22I and 222 complete the now reversed ringing circuit, whichmay be traced as follows: battery from interrupted generator, throughthe upper winding of the ring cut-off relay 2I0, contacts 203, 2I3, 222,243, Wiper 234 and its engaged designated contact, the negativeconductor of the called line and the ringer of the called station toground. The system now continues to function and release (when required)as previously described.

Executive cut-in Station H is shown as being assigned to an executiveand is equipped with a non-locking key such as I05, which provides theexecutive with "executive cut-in on busy lines. This special featurewill function as described in the following paragraphs.

It will be assumed that subscriber J is busy and executive H has dialedthe call number of subscriber J and received a busy tone. All operationsare the same as described in the previous section up to and includingcompletion of the busy .test circuit as wiper 231 encounters the groundsupplied by the seized connector link in use by subscriber J andmultipled to all th contacts of all connectors. This circuit wouldenergize the busy relay 250 over a path traced from ground encounteredby wiper 231, contacts 246, 212 and through the winding of relay 250 tobattery.

In operating contacts 252, relay 250 completes abusy tone circuit andbusy tone is transmitted to the executive in a well-known manner. Atcontacts 253, relay 250 opens a point in the operate circuit of thecut-through relay 220. At contacts 254 relay 250 prepares a lockingcircuit for itself, at contacts 255 prepares a circuit for the executivecut-in relay 260, at contacts 256 prepares a locking circuit for relay260 and at contacts 251 opens a point in the pulsing circuit.

Upon receipt of busy tone the executive may now depress his key I85 thuscompleting a circuit for the executive cut-in relay 260, this circuitextending from ground at key I85, conductor I24, contact 8 engaged bywiper I91, conductor I I1, through the upper winding of relay 260,contacts 225, 255 and through the lower winding of relay 260 to battery.In operating X contacts 266, relay 260 locks itself operated over itslower Winding, this circuit extending from the ground encountered bywiper 231 (from the busy line), contacts 246, 226, 256, X contacts 266and through the lower winding of relay 260 to battery. At contacts 26I,relay 260 removes busy tone from the executives line, at contacts 262and 254 the executive is directly connected with subscriber J formonitoring purposes or conversation, at contacts 265 the circuit to thebusy relay 250 is opened, at contacts 261 a point in the locking circuitof relay I40 is opened and at contacts 268 a different path in thelocking circuit of relay 260 is provided.

In restoring contacts 253, busy relay 250 prepares a circuit for thecut-through relay 220, at contact 255 a point in the original energizingcircuit to relay 260 is opened, at contacts 256 one of the points in thelocking circuit of relay 266 is opened and at contacts 251 a point inthe pulsing circuit is restored.

As previously mentioned, the executive may monitor or converse withsubscriber J. However, under present conditions, two finder-connectorlinks are in use, which is normally not desired in a small exchange ofthis type, therefore, the executive may request subscriber J to hang up.In hanging up and releasing the present connection between subscriber Jand his called party, the ground potential is removed from his controlconductor I15 and replaced by battery potential, thereby removing thebusy condition. As relay 260 was previously locked operated to thisground, the battery potential now encountered shunts relay 260 and itrestores.

At contacts '26I and 263, relay 260 restores the connections of thetalking conductors in the link to normal, at contacts 265 a circuit tothe cutthrough relay 220 is completed, this circuit extending fromground at contacts 229, conductor I28, contacts I33, conductor II6,contacts 265, 253, the lower winding of relay 220, contacts 21 I, 246and to the battery encountered by wiper 231. At contacts 266, 261 and268 relay 260 opens its previous locking circuit.

In operating, cut-through relay 226 operates as described in theprevious section. 'Ringing current is now transmitted to subscriber Jand upon his answering, the ring cut-off relay 2I0 operates aspreviously described. The executive may now converse with subscriber Jusing the normal connections employing only one finderconnector link.

Upon completion of conversation the equipment is released in the samemanner as described in the previous section.

Code call The followin description will cover the operation of theillustrated equipment in Figures 1., 2, 3 and 4 during the initiationand completion of a code call.

Referring to. the above-mentioned figures, it

, will be noted that only thosestations'whose extra control (E. C.)conductors are connected to the line finders (Fig. l) of thefinder-connector links and the code call finder (Fig. 3) of the codecall equipment can establish a code call. However, a. code call may beanswered from any subscribers station. It will also be noted, that forthe following description the E. C. conductor I24 of the executive H isconnected as described above.

In referring to the table, it will be noted that the code callinitiating number is the single digit 3 and that the code call answeringnumber is the three digit number 906.

It will be remembered that each subscriber whom it is decided to codering is given an individual two digit code call number, these numbersmay range from 11 through 66, therefore it is evident that a maximum of36 code calls may be rung by the illustrated equipment. It will beremembered that in the code call switch shown in Figure 4, the contactbanks accessible by the wipers 486 through 489 are connected as follows:the first six contacts of the bank accessible by wiper 486 are connectedconsecutively as shown; all but the last, or normal, contact of th bankaccessible by wiper 481 are multipled and connected to ground; the firstsix contacts of the bank accessible by wiper 488 areconnectedconsecutively as shown; the fourth contact of the bank accessible bywiper 489 is shown as connected to the second and sixth contacts of thebank accessible by wiper 48B and the fifth and sixth contacts aremultipled and then connected to the third contact of the ham; accessibleby wiper 488.

Assuming now that subscriber H wishes to talk to subscriber J and thatsubscriber J has been given the individual code number of 22. It is alsoassumed that subscriber H has called subscriber J in the usual manner asdescribed in the section entitled Local to local calls and has beeninformed that subscriber J is somewhere at large about the factory. V

Subscriber H may now remove his receiver and dial the single digit 3upon receipt of dial tone. The equipment in Figures 1 and 2 operates asdescribed in the above-mentioned section and after the last pulse of thedigit 3 is received it will be noted that motor magnet 280 has steppedits wipers 232 through 239 into engagement with their respective thirdcontacts. As wiper 238 engages its third contact, a circuit is preparedfor the relays 350 and 360. As wiper 236 engages its third contact aseries energizing circuit is completed for relays 220 and 300; thiscircuit extending from ground at contacts 229, conductor I28, contactsI33, conductor II6, contacts 265, 253, lower winding of relay 220,contacts 21I, 241, wiper 236 and engaged third contact, conductor 206,contacts 31I, 35I and through the winding of relay 300 to battery.

In operating contacts 30I, relay 300 completes a circuit to the linerelay 305 by way of its lower winding; this circuit extending fromground through the lower winding of relay 305, contacts 354, 30I and upto battery on the control conductor 304. Relay 220 operates as describedin the previous section entitled Local to local calls.

In operating, relay 305 completes a circuit to relay 3I0 at contacts306, this circuit extending from ground at contacts 311,306 and throughthe winding of relay 3 I to battery. In operating contacts 3| I, relay 3I 0 completes an obvious holding circuit for the relay 300 and theground at contacts 3 also serves to busy the code call finder to otherinitiated code calls during the present time that the code callequipment is in use. At contacts 3I2 a point in the energizing circuitto relay 330 is opened, at contacts 3I3 a circuit is prepared for relayM0, at contacts 3I4 an obvious circuit is prepared for relays 360 and350 and at contacts 3I5 an operative circuit is completed for the findermotor magnet 380 by way of contacts 358 and 36I.

Motor magnet 380 in operating, closes contacts 38I, thereby completingan obvious circuit to the relay 360. Relay,350 in operatin contacts 36Iopens the circuit to magnet 380 which now restores and advances wipers395 through 398 one step. Magnet 380 opens the circuit to relay 363 atcontacts 38I. In restoring, relay 369 again completes the circuit tomagnet 380 at contacts 36I. This inter-action between relay 360 andmagnet 380 c ntinues until the wipers 395 through 398 engage theirrespective 8th contacts. At this time wiper 398 encounters the groundpotential applied to the extra control (E. C.) conductor I24 of thecalling line by wiper 238 being engaged with its grounded 3rd contact,which completes aseries circuit for relays 260, 350 and 360. Thiscircuit may be traced as follows: from wiper 238 engaged with thegrounded 3rd contact, contacts 224, the upper winding of relay 260,conductor III, wiper I91 and engaged 8th contact, conductor I24, cableCI14, conductor I24, 8th

12 contact engaged by wiper 398, upper windings of relays 350 and 360,contacts 3I4 and to battery.

In operating X contacts 351, relay 350 completes an obvious lockingcircuit for itself over its lower winding to ground at contacts 3I5, atcontacts 35I the circuit to relay 300 is opened, at contacts 352 and 353the talking conductors of subscriber H are extended through into theequipment and line relay 305 is now maintained operated over the closedsubscribers loop and a second dial tone (this time from the code callequipment) is transmitted back to the calling subscriber in a well-knownmanner. Contacts 354 open a point in the previous energizing circuit ofrelay 305, contacts 355 apply ground to the control conductors of thecalling subscriber for busying said subscriber, contacts 356 alter theprevious energizing circuit for relays 350 and 363, however relay 350remains locked operated while relay 360 restores and at contacts 358 thecircuit to magnet 380 is maintained open. In operating, relay 360 opensthe circuit to magnet 330 at contacts 36I and remains operated only longenough for relay 350 to lock operated and open the circuit to magnet380. 7

Relay 260 operates as previously described in the section entitledExecutive cut-in. However, as cut-through relay 220 is energized andrelay 260 operates contacts 261, the locking circuit to relay I40 isopened and relay I40 restores. In restoring, relay I40 opens the circuitto line relay I20, which restores and opens the circuit to the holdrelay I30. Relay I30, in restoring, opens the holding circuit of thecut-through relay 220, which in restoring opens the circuit to relay 260and at contacts 230 completes the homing" circuit for motor magnet 280which steps its wipers 232 through 239110 normal. The finder-connectorlink is now completely released and conditioned for future calls and theexecutive is now connected with the code call equipment.

Relay 300 restores and opens another point in the first energizingcircuit of line relay 305 at contacts 30I Upon receipt of the seconddial tone, the exeoutive (subscriber H) dials the first digit2 of thecode call number 22 which is individual to subscriber J. Line relay 305will operate in the usual and well-known manner and deenergize andenergize two times. At the beginning of the first pulse, line relay 305will deenergize and at contacts 301 complete circuits to the seriesrelay 4H) and motor magnet 4| 3. This circuit may be traced as follows:from ground at contacts 311, contacts 391, 3I3, conductor 319 and 1) upthrough the lower winding of relay 4I0 to battery, (2) contacts 422 andthrough the winding of motor magnet 4I3 to battery. It will be notedthat due to their construction, relay 3I9 will remain operated duringdialing and relay 4I0 will remain oper-- ated during pulsing. Inoperating, relay 4I0 opens contacts 4I2, thereby removing ground fromwipers 488 and 489 while pulsing. At the end of the first pulse, relay305 reenergizes and the circuit to relay M0 and magnet M3 is opened,however, only magnet4l3 restores and in restoring rotates wipers 485through 489 one step. At the beginning of the second pulse, relay Mil ismaintained operated and magnet M3 is again energized in the same mannerwhen relay 305 restores. At the end of the second pulse, relay 395 againreoperates and as this is the last pulse of the first digit, relay 4I0re- 489 another step so that now the Wipers are engaged with theirrespective second contacts. vAs relay 419 restores contacts 412, acircuit is completed for storage relay 458, which may be traced fromground at contacts 315, conductor 384, contacts 426, conductor 383,contacts 331, conductor 382, contacts 412, wiper 48.8'and engaged secondcontact, break contact of armature 443 and through the winding of relay460 to battery.

In operating contacts 461 through 464, relay 468 prepares various pathsfor future markings of the contacts accessible by wiper 486. At contacts465 relay 468 prepares a future circuit for itself in series with relay449 and at contacts 466 completes a circuit for the relay 338. Thiscircuit extending from ground at contacts 315, conductor 384, contacts426, conductor 383, contacts 33?, conductor 382, contacts 412, wiper4.88 and engaged second contact, armature 44.3 .and break contact,contacts 465, 466, 445, up over conductor 362 and through the winding ofrelay 339 to battery.

In operating, relay 339 looks itself operated over. an obvious circuitto the multiple grounded contacts accessible by wiper 48? at X contacts332. At contacts 331 a point in the dial tone circuit is opened, atcontacts 334 a point in the operate circuit of relay 469 is closed, atcontacts 335 an obvious circuit is completed to motor magnet 413 fromground encountered by wiper 491', at contacts 336 a point in analternate energizing circuit for magnet 413 is opened and at contacts33'! ground is removed from wipers 488 and 489. Relay 448, however, nowhas ground applied on both sides of its winding and cannot operate.Relay 469 is maintained operated by the same ground applied on therighthand side of relay 446.. This circuit may be traced from groundencountered by wiper 481, conductor up through X contacts 332, conductor362. down to contacts 445, 466, 465 and through the winding of relay48.9 to battery.

In operating, magnet 413 opens its energizing circuit at contacts 414and thereby restores. In restoring, magnet 413 advances its wipers 486through 489 one step and recloses its own-circuit at contacts 414. Thisinteraction between magnet 413 and its contacts 414 continuesun'tilwipers 496 through 489 have restored-to normal. At this time noground is encountered by wiper 481 and relay 338 restores, and thelast-traced operating circuit for relay 469 is opened. However, nowrelay 469 remains operated over .a circuit in series withlrelay 441] andrelay 44!) operates. This circuit may be traced from ground at contacts315, down through conductor 384, through the winding of relay 448, upthrough contacts 485 and through the winding of relay 469 to battery. Inoperating armatures 442 through 444 with their respective make contacts,relay 449 prepares circuits for the second .group of storage relays soas to be able to store the second digit of the code call number whendialed, at contacts 445 a point is opened in the second holding circuitfor relay 468 and at armature 441 and its breakcontact, dial tone isfurther removed from the calling line.

The second and last digit 2 of the :code call number 22 is now dialedand line relay 385 deenergizes and energizes twice in response to thepulses of the second digit in the same manner as previously describedfor the first digit- Relay w 14 419 and magnet 413 also operate aspreviously described for the first digit and it will be noted that afterthe end of the last pulse and after relay 385 has again energized,wipers 486 through 489 will have stepped to their second contacts asmagnet 413 restores and as relay 418 restores contact 412, ground isapplied to wipers 488 and 489 and a circuit is completed for the storagerelay 499 over a path similar to that traced for the storage relay 460.In operating contacts 49:1 through 494'relay 498 prepares various pathsfor future markings of contacts accessible by wiper 486 and at contacts495 and 496 a circuit is completedfor relay 338 over a path similar tothe one previously described by relay 468.

Relay 339 operates as previously described to energize magnet 413 andmagnet 413 operates and restores to return the switch to normal also aspreviously described. Relay 498 is maintained operated and relay 429 isshunted over circuits similar to the ones traced for relays 468 and 448.After the switch has been'restored by magnet 413, magnet 413 and relay338 restore. The shunt is removed from both sides of relay 428 and relay428 operates in series with relay 498 over a circuit similar to the onetraced for relays 469 and 449.

In operating contacts 421 relay 420 applies a marking potential to thesecond and sixth contacts accessible by wiper 486. This marking groundmay be traced as follows: from ground at contacts 482, contacts 421, tothe left to the sixth contact, and to the right to armature 41-2 andbreak contact, contacts 463, 452, 434 and up to the second contact. Atcontacts 422,,relay 429 opens the pulsing circuit to motor magnet 413,at contacts 424 a point in the last-mentioned energizing circuit ofrelay 330 is opened, at contacts 4.25 a circuit is completed for relay345 which may be traced from ground at contacts 315, conductor 384,contacts 425, conductor 389,

contacts 327, 3715, 343 and through the winding of relay 345 to battery.The operation of the equipment for the first code ringing cycle will nowbe discussed.

Relay 345 is constructed as being slow to operate, however, upon eachoperation of contacts 346 a splash of dial tone is sent out over thecalling line thereby indicating to the calling subscriber the code beingrung, at contacts 348 an obvious circuit is completed to theslow-tO-opera-te relay 348 and at contacts 349 a circuit is completed tothe relay 3.65. This circuit extendi-ng from ground at contacts 339,conductor 392,

contacts 491, conductor 399, contacts 349 and through the winding ofrelay 365 to battery. Relay 3.65 completes an obvious circuit to codevsounders such as 398 and 391 at contacts 366,

thereby causing them to operate and ring once. Relay 3411- hascompletely operated and at contacts 342 prepares a circuit for magnet413 and opens the circuit to relay 345 at contacts 343, which allowsrelay 345 to restore. In restoring, relay 345 opens the circuit to relay365 at contacts 349 and contacts 348 opens the circuit to relay 349.Before slow-to-operate relay 340 has had time to release, however, acircuit is completed to magnet 413 at contacts 341, this-circuitextending from ground at contacts 34'], contacts 3'14, 342, 336,conductor 368, contacts 423 and through the winding of magnet 413 tobattery.

Magnet 413 operates and prepares to rotate its wipers 486 through 489.Relay 348 now restores and in-so doing opens the circuit to magnet 411315 at contacts 342. Magnet 3 advance its wipers one step upon releasing.Relay 340, in restoring contacts 343 completes the previously tracedcircuit to relay 345. In operating, relay 345 again completes circuitsto relays 365 and 340 and at contacts 346 a second splash of dial toneis sent out over the calling line. Relay 365 operates and completes thecircuit to the code sounders causing them to ring a second time. Inoperating, relay 340 again opens the circuit to relay 345 and preparesthe circuit for magnet 4|3. Relay 345, in releasing, opens the circuitsto relays 385 and 340 and again completes the circuit to magnet 413.Relay 365 releases and magnet 4I3 operates, after which, relay 340completely restores and opens the circuit to magnet 4l3. Relay 345 isconstructed so as to be slow to operate and also somewhat slow torelease, therefore magnet 4| 3 restores and advances its wipers a secondstep, completing a circuit for relay 330, which extends from batterythrough the upper winding of relay 330, conductor 362, wiper 486 andits'engage'd marked second contact, contacts 434, 452, 463, 412, 42l and402 to ground. In operating, relay 330 opens the last-mentionedoperating circuit of magnet M3 at contacts 336, at contacts 335completes a circuit to magnet M3 by way of wiper 481, at contacts 338completes a circuit to prepare for operating relay M5 in its first step,opens a point in the circuit to relay 365 at contacts 339 and at Xcontacts 332 locks itself operated to the ground encountered by wiper481. Relay 5 does not operate at this time since the ground extendingfrom contact 338 energizes both the upper and lower winding inopposition. The circuit for the upper winding of relay 5 may be tracedfrom ground at contacts 338, conductor 393, contacts M9, 421, the upperwinding of relay 5, contacts 429 and the associated resistance tobattery. The circuit for the lower winding of relay 5 may be traced overa similar path, but extending through the lower winding directly tobattery. Magnet 4|3 operates, prepares to step its wipers, opens its owncircuit at contacts 4 and restores, thereby advancing wiper 486 through409 one step. Magnet 3 continues to operate and restore in the samemanner until the wipers are restored to normal (as shown) at which timewiper 481 no longer encounters ground and magnet 4 I 3 and relay 330restore. As relay 330 restores contacts 38, the circuit is opened torelay 4| 5. However the opening of the circuit to relay 5 causes aninductive surge of current inthe windings of the relay, resulting in theclosing of X contacts 418 (first step operation). The closing of Xcontacts 4| 8 completes a series aiding circuit through both windings ofrelay 5 causing it to operate fully (second step). This circuit may betraced as follows: from ground at contacts I 5, contacts 386, conductor381, X contacts 418, upper winding of relay 5 and the lower winding ofrelay 5 t battery. The two windings of relay 415 now aid in theoperation of relay 5 through its second step. In restoring contacts 339,relay 330 again prepare a circuit to relay 365. In operating, relay 5completes an obviou circuit for the relay 430 at contacts 6, at contacts4l1 prepares a circuit for relay 400, at contacts 429 removes thebattery and resistance from the upper winding of relay 5 and at contacts4|9 opens the first energizing circuit of relay 4 l 5.

In operating armatures 43| through 435 with their respective makecontacts, relay 430 completes the marking circuit for marking the conthecalling line at contacts 40I, at contacts 402 tact, corresponding to thesecond digit of the code call number, accessible by wiper 486. Themarking of the contact may be traced as follows: from ground at contacts402, contacts 42!, and to the left t contact number 6, and to the rightthrough contact 411, 493, 492, and the make contact of armature 434 upto the second contact of the contact bank.

It will be noted that relays 345 and 340 have continued to operate anddeenergize one another. However their operations have no efiect on theequipment until relay 330 restores, at which time the closing ofcontacts 339 prepares a circuit for relay 365 as mentioned above. Duringthe subsequent operation of relay 345 a previously traced circuit isagain completed to relay 365 at contacts 349. Relay 345 also completes acircuit to relay 340, however relay 365 operates, completing a circuitto code sounders such as 390 and 3!" causing them to ring once. Relay340 now operates and prepares a circuit to magnet H3 and opens thecircuit to relay 345 at contacts 342 and 343 respectively. In restoring,relay 345 opens the circuit to relay 340 and completes a previouslytraced circuit to magnet M3 at contacts 348 and 341 respectively and atcontacts 349 opens the circuit to relay 365 which now restores. Inoperating, magnet 4l3 prepares to step its wipers 486 through 489. Relay340 now restores and opens the circuit to magnet M3 and completes thecircuit to relay 345. Magnet 4| 3 restores and advances its wipers onestep. In operating, relay 345 again completes the circuit to relays 340and 365. In operating, relay 365 again completes the circuit to codesounders such as 390 and 39| causing them to ring a second time. Relay340, in operating opens the circuit to relay 345 and prepares a circuitfor magnet 3. In restoring, relay 345 opens the circuit to relays 340and 365 and completes the circuit to magnet 4 I 3. Magnet 3 againprepares to advance its wipers and in restoring, relay 340 opens thecircuit to magnet H3 and completes the circuit to relay 345. Magnet 4l3restores and advances its wipers a second step. However, before relay345 ha had time to again operate and as wiper 406 engages its markedsecond contact, a previously traced circuit from ground at contacts 402is completed to relay 330.

Relay 330 operates as previously described, with the exception that atcontacts 334 a circuit is prepared for operating relay 400 in its firststep. Relay 400'is similar to relay 5 and does not operate at this time.A homing circuit is completed to magnet 413 at contacts 335 by relay 330and therefore magnet 4l3 restores its wipers to normal, at which timethe circuit to relay 330 is opened and relay 330 restores. As relay 330restores contacts 334, the circuit is opened to relay 400. However, theopening of the circuit to relay 400 causes an inductive surge of currentin the windings of the relay 400, resulting in the closing of X contacts405 (first step operation). The closing of X contacts 405 completes aseries aiding circuit through both windings of relay 400 causing it tooperate fully (second step). This circuit may be traced from ground atcontacts 3 l 5, contacts 386, conductor 381, X contacts 405, through thelower winding of relay 405 and the upper winding of relay 405 tobattery.

In operating, relay 400 removes dial tone from and 403 the markingground is removed from one circuit path and changed to another so thatnow the third contact available by wiper 486. is marked with the groundpotential. This circuit may be traced from ground at contacts 403' up tothe third contact. At contacts 404, battery and resistance are removedfrom the lower winding of relay 400, at contacts 406, an alternateenergizing path for relay 345 is opened but relay 345 may still operateover the previously described one, at contacts 401 a point in thecircuit of relay 365 is opened and at contacts 403 prepares a point inthe circuit of relay 385.

In operating, relay 3'45 completes the circuit for relay 340, which uponoperating, prepares a circuit for magnet 413 and opens the circuit forrelay 345 as described before. Relay 345, in restoring, opens thecircuit for relay 340 and completes the circuit for magnet 4I3. Inrestoring, relay 340 opens the circuit to magnet M3 and again completesthe circuit to relay 345. In restoring, magnet 4I3 advances its wipersone step. This inter-action between relays 345 and 343 in connectionwith magnet 4I3 continues until the restoration of magnet 4 I3 steps itswipers to their third contacts, at which time, wiper 483 encountersground on its marked third contact and completes a previously tracedcircuit to relay 330. During this third operation of the code callswitch it will be noted that the relay 365 is not operated to operatethe code sounders 390 and 39! to create a pause between codes.

In operating contacts 335, relay 330 completes a previously describedcircuit for operating magnet 4I3 and at contacts 338 a circuit iscompleted for relay 335, this circuit extending from ground at contacts338, conductor 333, down through contacts 438, conductor 394 and throughthe winding of relay 385 to battery. In operating, magnet 4I3 restoresits wipers to normal in the same manner as previously described. Inoperating contacts 386, relay 385 opens the circuit to relays 400 andM5. If magnet 4I3 has not fully restored its wipers to normal, as relayM5 restores, a circuit would be prepared for relay 4I5, but it could notstay energized and therefore would not affect the equipment. Assuming,however, that magnet 4I3 has restored its wipers and thereby opened thecircuit of relay 330, which in restoring will open the circuit to relaysM5 and 385 at contacts 338. As relay 385 is made slow-torelease thecircuit to relay M5 is open at contacts 383 and relay 4I5 will stayrestored. The first code ringing cycle has now been completed.

Relay 345 will operate and start a second code ringing cycle, operatingthe equipment in the same manner as described for the first cycle. Thecode ringing will continue until the paged party answers the call or thecalling party replaces his receiver to thereby release the connection.

After hearing his code being rung the paged party (subscriber J) answersthe code call by dialing the common three digit code call answeringnumber 906. In answering, subscriber J removes the receiver of thetelephone from the nearest station and seizes a finder connector linksuch as shown in Figures 1 and 2 in the same manner as described in thesection entitled Local to local calls. The code call answering number906 is then dialed and the equipment operates in the same manner asdescribed in the abovementioned section, with the wipers of theconnector stopping on their 9th contacts in response to the 1st digits,stopping on their 19th contacts after the 2nd digit, and finallystopping on their 25th contact after the third digit. Upon completion ofdialing the last digit, it will be found that the equipment is operatedsuch that the call corresponds to. a first line group call and wipers2.32, 234 and 236 of the connector are en gaged with their respective thcontacts. As wiper 236 engages its 25th contact a circuitiS completedfor the cut-through relay 220, this circuit extending from ground atcontacts 229, conductor I28, contacts I33, conductor H6, contacts 265,253, the lower winding of relay 220, contacts 27I, 241, wiper 236 andits engaged 25th contact, conductor 304, cable C344 and to theresistance and battery on conductor In operating contacts 22I and 222,relay 220 completes a series circuit for ring out 01f relay 2 I 0 andthe answering relay 320. This circuit being traced as follows: ground atcontacts 204, contacts 213, 222, 243, wiper 234 and engaged 25thcontact, conductor 303, cable C344, conductor 303, contacts 324, upperwinding of relay 320, contacts 322, conductor 302, cable C344, conductor302, 25th contact engaged with wiper 232, contacts 2M, 22I, 2| I, 2M andthrough the upper winding of relay 2I0 to battery at interruptedgenerator.

Relay 2I0 operates as described in the previously mentioned section andin operating, relay. 320 closes X contacts 323 to complete a h01dingcircuit from ground at contacts 3 I 5 through its lower winding andcloses contacts 32I and 323 to thereby connect the talking conductors ofthe answering line (subscriber J) with subscriber H. At contacts 322 and324 relay 320 opens its original energizing circuit, at contacts 325 analternate maintaining circuit for relay 3I0 is completed to provide forlast-party-release of the code call equipment and at contacts 321 analternate circuit is opened to relay 345. The code ringing will continueuntil the code sending cycle has been completed, at which time the fulloperation of relay 400' will open the other circuit to relay 345. Relay345' in restoring, opens the circuit to relay 340, thereby stopping theequipment from sending further codes. The talking connection from thecalling subscriber H and the called subscribed J is now completed andincludes the code call finder connected directly to the calling line,the code call circuit, and the finder-connector link used by the calledsubscriber J in answering his code call. The talking connections includethe heavy talking conductors. Talking battery for the calling line beingfed through line relay 305, while talking battery for the called line isfed through line relay such as I20 of the finder-connector link.

After conversation and in response to the replacing of the receivers,the equipment is released in the following manner: the finder-connectorlink is released in the same manner as described in the previous sectionentitled Local to local calls and the release of the code call equipmentis initiated by the last party to replace his receiver.

When the called subscriber J replaces his receiver the line relay I20and release relay I30 in the finder-connector link release as previouslydescribed. The restoration of relay I30 opens the locking circuit torelay 220 which restores and disconnects ground at contacts 228 fromwiper 236 and conductor 304 thereby removing one of the grounds whichholds release relay 3I0 of the code call switch operated throughcontacts 325. When the calling subscriber H replaces his receiver theline relay 305 of the code call switch restores and at contacts 306 alsodisconnects one of the grounds which holds release relay 3I0 operated.Therefore, the last party to restore his receiver'releases relay 3I0.When the hold relay 3I0 restores contacts 3I5, relays 350, 320, M0, 420,440', 460 and 490 restore. Relay 350 removes the busy condition from thecode call finder and the code call equi ment is at normal and ready tohandle future calls.

Special alarm rupted signal which may be initiated by any equipment thatwill apply a ground potential to the special cod-e alarm lead. Thegrounding means as illustrated in Figure 3 is a locking key such as 328.

Assuming for the present that the code call equipment is idle, a specialalarm may be initiated and sent in the following manner: key 328 isclosed and locked, thus completing an obvious circuit for relay 310. Inoperating contacts 312, relay 310 completes a busying circuit for anyincoming code calls, at contacts 313 a circuit is prepared for relay330, at contacts 314 the circuit to magnet H3 is opened. at contacts 316an obvious circuit is completed for relay 345 and at contacts 318prepares a circuit for relay 365. Relay 345 operates as described in theprevious section, completing circuits for relays 340 and 365 at contacts348 and 349 respectively. Relay 365 operates as previously described,completing the circuits to the code sounders such as 390 and 39I,causing them to ring once. Relay 340 opens the circuit to relay 345allowin relay 345 to restore. In restoring, relay 345 opens the circuitto relays 365 and 340 and in restoring relay 34D completes the circuitto relay 345. Relay 345, in energizing again completes the circuit torelays 340 and 365. This interaction between relays 340 and 345continues to cause relay 365 to operate the code sounders until the key328 is released, at which time relay 310 restores, causing relay 345 torestore and which in turn releases relays 340 and 365.

Assuming now that the code call equipment is in use and that relay 310is operated in the middle of a sending cycle, as relay 310 closescontacts 313 a circuit will be completed for relay 330, this circuitextending from ground encountered by wiper 481, conductor 363, contacts313, conductor 362 and through the upper winding of relay 330 tobattery. Relay 330, in operating contacts 335 completes a previouslytraced circuit for magnet M3 and wipers 486 through 489 are advanced tonormal. During the above mentioned operation, relay 310 has operatedrelay 345, which in turn operates relays 340 and 365, causing the alarmto be sent out in the same manner as described in the above paragraph.Upon completion of the alarm being sent out, relay 310 is restored tonormal and the equipment prepares to code ring the desired party bystarting at the beginning of a ringing cycle in which relay 345 operatesrelay 365 to give the first ring and operates relay 340 to interrupt thecircuit of relay 345 and prepares motor magnet M3 for stepping itswipers. The remainder of the operation of the equipment and its releasebeing described in the previous section entitled Code call.

Having described the invention, what is considered new and is desired tohave protected by Letters Patent will be pointed out in the followingclaims.

What is claimed is: I I

1. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of party linesterminating in the first set of bank contacts and accessible to thefirst wiper set, a second group of party lines terminating in the secondset of bank contacts and accessible to the second wiper set, a first anda second station on said party lines, a ring determining position and awiper switching position terminating in said bank contact sets, meansfor directively operating said wipers of said switch in response to thereceipt of incoming digits to stop said wipers in engagement with saidbank contacts in accordance with the received digits, ring determiningapparatus in said switch operated in response to said switch wiperstopping in engagement with said ring determining position forthereafter selectively signalling the second stations of said lines ineither line group, and wiper switching apparatus in said switch operatedin response to said switch wiper stopping in engagement with said wiperswitching position for switching from said first set of wipers to saidsecond set of wipers to extend calls to said second group of lines.

2. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of lines terminating inthe first set of bank contacts and accessible to said first set ofwipers, a second group of lines terminating in the second set of bankcontacts and accessible to said second set of wipers, a wiper switchingposition terminating in a bank contact in said first bank contact set, acode calling position terminating in a bank contact in said first bankcontact set, a called subscribers line in said second line groupterminating in bank contacts in said second bank contact setcorresponding to said code calling position bank contact in said firstbank contact set, code calling apparatus for code signalling calledsubscribers who are away from their telephones, means for directivelyoperating the wipers of said switch in response to the receipt ofincoming digits to stop said wipers in engagement with said bankcontacts in accordance with said received digits, wiper switchingapparatus in said switch operated in response to said wipers stopping inengagement with said wiper switching position bank contact for switchingfrom said first wiper set to said second wiper set to extend calls tolines in said second line group, means for completing a connection withsaid called subscribers line in case said switch wipers subsequentlystop in engagement with said bank contacts corresponding to said calledsubscribers line and said code calling position after initially stoppingin engagement with said wiper switching position, and means forinitiating the operation of said code call apparatus in case said switchwipers initially stop in engagement with said code calling position bankcontact and the bank contacts of said called subscribers line.

3. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of party linesterminating in the first set of bank contacts and accessible to thefirst wiper set, a second group of party lines terminating in the secondset of bank contacts and accessible to the second wiper set, meansincluding a motor magnet in said switch operated responsive to impulsesreceived from one of said lines when calling, for directively operatingsaid wipers in one, two, three, four, or five directive movements tocomplete connections to various ones of said lines, a source ofsignalling current,

circuitmeans including a pluralityof relays controlled responsive tosaid directive movements,

to selectively signal only one of the first parties in either line groupon each call in case the called line was connected with in one, two,three, or four directive movements, and said last means dependent upon apredetermined first directive movement connecting said source to anotherone of said wipers in either wiper set to selectively signal only one ofthe second parties ineither line group on each call in case the calledline was connected with in two, three, four, or five directivemovements.

4. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of party linesterminating in the first set of bank contacts andaccessible to the firstwiper set, a second group of party lines terminating in the second setor" bank contacts and accessible to the second wiper set, meansincluding a motor magnet in said switch-operated responsive to impulsesreceived from one of said lines when calling, for directively operatingsaid wipers in one, two, three, four, or five directive movements tocomplete connections to various ones of said lines; a source ofsignalling current, circuit means and a plurality of relay means'controlled responsive to said directive movements, for controlling saidcircuit means to connect said source of signalling current to one ofsaid wipers in said first set in case the called line is connected within one, two, or three directive movements to selectively signal only thefirst parties in said said first party line groups, wiper switchingmeans included in said relay means operated dependent upon apredetermined first directive movement, for connecting said source ofsignalling current to a corresponding one of said wipers in said secondset in case the called line is connected with in two, three, or fourdirective movements to selectively signal only the first parties in saidsecond party line group; and ring reversing means included in said relaymeans operated dependent upon a different predetermined first directivemovement for connecting said source of signalling current to a secondone of said wipers in said first set in case the called line isconnected with in two, three, or four directive movements to Iselectively signal only the second parties in said first party linegroup and said ring reversing means and said wiper switching meansoperated dependent on two successive difierent predetermined firstdirective movements for connecting said source of signalling current toa corresponding second one of said wipers in said second set in casesaid called line is connected with in three, four, or five directivemovements to selectively signal only the second parties in said secondparty line group.

5. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of party linesterminating in the first set of bank contacts and accessible to thefirst wiper set, a second group of party lines terminating in the secondset of bank contacts and accessible to the second wiper set, meansincluding a motor magnet in said switch operated responsive to impulsesreceived from one of said lines when calling, for directively operatingsaid wipers in one, two, three, four, or five directive movements tocomplete connections to various ones of said lines; a source ofsignalling current, circuit means and a plurality of relay means con-'for controlling said circuit means vto connect said -source to one ofsaid wipers in either wiper set trolled responsive 'to said directivemovements, for controlling said circuit means to connect said source ofsignalling current to one of said wipers in said firstset in case thecalled line is connected with in one, two, or three directive movementsto selectively signal only the first parties in .said first party linegroup, said plurality of relay means controlled in another instance forcontrolling said circuit means to connect said source of signallingcurrent to a corresponding one of said wipers in said second set in casethe called line is connected with in two, three, or four directivemovements to selectively signal only the first parties in said secondparty line group; said plurality of relay means controlled in a furtherinstance for controlling said circuit means to connect saidsource ofsignalling current to a second one of said wipers in said first set incase the called line is connected with in two, three, or four directivemovements to selectively signalonly the second parties in said firstparty line group, said plurality of relay means controlled in a lastinstance for controlling said circuit means to connect said source ofsignalling current to a corresponding second one of said wipers in saidsecond set in case said called line is connected with in three, four, orfive directive movements to selectively signal only the second partiesin said second party line group; ring reversing means included in saidrelay means and controlled responsive to the first predetermineddirective movement of the wipers for determining that the second partiesin either line group will be selectively signalled by said source, andwiper switching means includedin said relay means and controlledresponsive to a different first predetermined movement of said wipers,or a second predetermined directive movement of the wipers followingsaid first predetermined directive movement for determining that thesaid corresponding wipers in said second set will be used to selectivelysignal only the parties in said second line group.

6. In a telephone system, a single level automatic switch having twosets of wipers and bank contacts, a first group of party linesterminating in the first set of bank contacts and accessible to thefirst wiper set, a second group of party lines terminating in the secondset of bank contacts and accessible to the second wiper set, a first anda second station on said party lines, a ring determining positionterminating in said bank contact sets, means for directively operatingsaid wipers of said switch in response to the receipt of incoming digitsto stop said wipers in engagement with said bank contacts in accordancewith the received digits, ring determining apparatus in said switchoperated in response to said switch wipers stopping in engagement withsaid ring determining position for thereafter selectively signalling thesecond stations of said lines in either line group and supplying batteryfeed to all said second stations of either line group.

'7. In a telephone system, a line, means for at times making said linebusy, a control conductor associated with said line and groundedwhenever said line is busy, a connector switch having access to saidline, a busy relay and a cut-in relay included in said switch, anexecutives line, means operated in response to the calling of said lineby said executive when said line is busy for causing said switch toconnect with said grounded conductor, said busy relay initiallyenergized in response to said connection with said grounded controlconductor and subsequently locked energized independently thereof, meansresponsive to said busy relays operation for completing a busy tonecircuit to said executive, means controlled by said executive foroperating said cut-in relay after hearing said busy tone, means forreleasing said busy relay in response to said operation of said cut-inrelay, a circuit for locking said operated cut-in relay energized oversaid grounded control conductor and for releasing said cut-in relay inresponse to the removal of ground from said control conductor when saidline becomes idle, and a signalling circuit completed to said line inresponse to the release of said cut-in relay.

8. In a telephone system, a plurality of connector switches having bankcontacts and wipers accessible thereto, a normal position bank contactfor each of said wipers, a distributor relay individual to each of saidconnector switches, said distributor relays being operated when theirassociated connector switches are idle and restored when theirassociated connector switches are busy, a reset relay, an operatingcircuit for said reset relay, contacts controlled responsive to therestoring of the last of said distributor relays in rotation forcompleting said operating circuit to operate said reset relay,distributor relay circuits completed responsive to the operation of saidreset relay for energizing all said distributor relays corresponding toidle ones of said connector switches, a locking circuit for eachdistributor relay including a wiper and said normal position bankcontact of its corresponding connector switch for maintaining saidenergized distributor relays in their operated positions, and a chaincircuit controlled by said operated distributor relays for allottingsaid idle connector switches for use in rotation.

9. In a telephone system as claimed in claim 8 including meanscontrolled over said chain circuit for seizing said allotted idleconnector switches for use in rotation, means for releasing eachdistributor relay by opening said locking circuits in response to theseizing of the corresponding con- 1 nector switch, and a series circuitcontrolled by all said distributor relays in their released positionsfor operating said reset relay to thereby reoperate the distributorrelays corresponding to idle connector switches over said distributorrelay circuits.

10. In a telephone system, a plurality of connector switches havingwipers and bank contacts accessible thereto, a normal position bankcontact for each of said wipers, a distributor relay individual to eachof said connector switches, means for momentarily energizing all of thedistributor relays corresponding to idle ones of said connector switchesto prepare said idle connector switches for seizure in rotation, and alocking circuit for each distributor relay including the normal positionbank contact of the associated switch for maintaining said energizeddistributor relays in their operated positions after said momentaryenergizations only in case each said locking circuit is completed over awiper and said normal posi- 24 tion bank contact of its correspondingconnector switch.

11. In a telephone system, a switch having access to a plurality ofcontact banks, a calling station, a first and a second group of storagerelays, means including a wiper in said switch operated responsive toimpulses received from said calling station for selecting a certainrelay of said first and a certain relay of said second groups of saidstorage relays, means for operating said selected storage relays,contacts controlled by said operated selected relays for placing amarking potential at certain contacts on a certain one of said contactbanks, and means for again operating said switch to transmit signals inaccordance With said marking potential.

12. In a code calling system, code call numbers each comprising twodigits, a calling station, means at said calling station for dialing adesired one of said code call numbers to thereby transmit trains ofimpulses corresponding to said digits, a first and a second group ofstorage relays, a code call switch having access to a plurality ofcontact banks, means including a wiper in said code call switch operatedresponsive to receipt of said impulse train corresponding to said firstdialed digit for selecting a certain relay of said first storage relaygroup, means for causing said switch to release subsequent to said firstoperation of said switch; said second means and said wiper of saidswitch reoperated responsive to receipt of said impulse traincorresponding to said second dialed digit for selecting a certain relayof said second storage relay group, means for causing said switch torelease subsequent to said second operation of said switch, means foroperating said selected storage relays, and contacts controlled by saidoperated storage relays for marking certain contacts on a certain one ofsaid contact banks.

13. A code calling system as claimed in claim 12 including means forreoperating said switch a third and a fourth time for transmitting codescorresponding to said markings, means for causing said switch to releasesubsequent to said third and a fourth operations of said switch, andmeans for reoperating said switch a fiith time to a third contact ofsaid certain contact bank for creating a silent interval between codes.

ROY W. JONES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,546,113 Albert July 14, 19251,732,186 Wicks Oct. 15, 1929 1,877,883 Kahn Sept. 20, 1932 1,889,229Tharp Nov. 29, 1932 2,137,518 Wicks Nov. 22, 1938 2,239,902 PetersonApr. 29, 1941 2,322,966 Erwin -1 Oct. 26, 1943 2,424,281 McClew et al.July 22, 1947

